Method and apparatus for selectively filtering residue from a processing chamber

ABSTRACT

The processing system comprises a pump assembly, a bypass assembly, and a processing chamber, which together form a circulation path. The bypass assembly is configured so that in a first mode, a filter does not form part of the circulation path, and in a second mode the filter does form part of the circulation path. Thus, the processing system is placed in the first mode when a processing material circulated over the circulation path does not need to be filtered. The processing system is placed in the second mode when a processing material circulated over the circulation path must be filtered.

FIELD OF THE INVENTION

This invention relates to the field of processing systems. More particularly, this invention relates to the field of selectively filtering residue from a semiconductor processing chamber.

BACKGROUND OF THE INVENTION

During a processing cycle, a semiconductor processing system introduces photoresist and other materials into a processing chamber to process a semiconductor wafer. During a later cleaning cycle, cleaning materials are introduced into the processing chamber to remove particles, such as etch residue, and other contaminants generated, for example, during the processing cycle. The processing chamber forms part of a circulation path used to circulate both processing materials and cleaning materials over a wafer in the processing chamber in one or more processing cycles. To ensure that the particles removed from the wafer surface are not reintroduced into the processing chamber, circulation paths generally employ a filter to trap and remove these particles before they can reenter the processing chamber.

As part of the circulation path, filters are exposed to materials during cleaning cycles and processing cycles, even those cycles that do not require filtration. For example, during an etching or a chemical vapor deposition process cycle, a filter is not needed. A filter placed in the circulation path is exposed to harsh chemicals and operating conditions used in the processing cycle. These harsh chemicals and operating conditions can shorten a filter's life, requiring that it be replaced more often than necessary. Replacing filters increases the time and cost of the entire device fabrication process because the processing system must be shut down to allow the filters to be replaced.

Accordingly, what is needed is a system and method for extending the life of a filter used in a circulation path.

SUMMARY OF THE INVENTION

One embodiment of the invention includes a processing system that includes a processing chamber having a processing chamber inlet and a processing chamber outlet; a recirculation subassembly having an inlet coupled to the processing chamber outlet and an outlet coupled to the processing chamber inlet, where the recirculation subassembly comprises a pump assembly and a bypass assembly coupled to the pump assembly, the bypass assembly comprising a first branch and a second branch; and a controller coupled to the bypass assembly for switching the bypass assembly between a first mode and a second mode, wherein when the bypass circuit is in a first mode, a first path is establish through the recirculation subassembly that includes the pump assembly and the first branch, and when the bypass circuit is in a second mode, a second path is establish through the recirculation subassembly that includes the pump assembly and the second branch.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of various embodiments of the invention and many of the attendant advantages thereof will become readily apparent with reference to the following detailed description, particularly when considered in conjunction with the accompanying drawings, in which:

FIG. 1 shows an exemplary block diagram of a processing system in accordance with an embodiment of the invention;

FIG. 2 illustrates a simplified block diagram of a recirculation subassembly in accordance with an embodiment of the invention; and

FIG. 3 illustrates an exemplary graph of pressure versus time for a supercritical process step in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS

The invention is a processing system having a circulation path that selectively includes one or more filters. The processing system comprises a pump assembly, a bypass assembly, and a processing chamber, which together form a circulation path. The bypass assembly is configured so that in a first mode, a filter does not form part of the circulation path, and in a second mode the filter does form part of the circulation path. Thus, the processing system is placed in the first mode when a processing material circulated over the circulation path does not need to be filtered. The processing system is placed in the second mode when a processing material circulated over the circulation path must be filtered. The second mode can be used, for example, when a processing material has collected residue and other contaminants generated while processing a semiconductor wafer. This structure advantageously extends the life of the filter.

FIG. 1 shows an exemplary block diagram of a processing system in accordance with an embodiment of the invention. In the illustrated embodiment, processing system 100 comprises a process module 110, a recirculation system 120, a process chemistry supply system 130, a carbon dioxide supply system 140, a pressure control system 150, an exhaust system 160, and a controller 180. The processing system 100 can operate at pressures that can range from 1000 psi. to 10,000 psi. In addition, the processing system 100 can operate at temperatures that can range from 40 to 300 degrees Celsius.

The controller 180 can be coupled to the process module 110, the recirculation system 120, the process chemistry supply system 130, the carbon dioxide supply system 140, the pressure control system 150, and the exhaust system 160. Alternately, controller 180 can be coupled to one or more additional controllers/computers (not shown), and controller 180 can obtain setup and/or configuration information from an additional controller/computer.

In FIG. 1, singular processing elements (110, 120, 130, 140, 150, 160, and 180) are shown, but this is not required for the invention. The semiconductor processing system 100 can comprise any number of processing elements having any number of controllers associated with them in addition to independent processing elements.

The controller 180 can be used to configure any number of processing elements (110, 120, 130, 140, 150, and 160), and the controller 180 can collect, provide, process, store, and display data from processing elements. The controller 180 can comprise a number of applications for controlling one or more of the processing elements. For example, controller 180 can include a GUI component (not shown) that can provide easy to use interfaces that enable a user to monitor and/or control one or more processing elements.

The process module 110 can include an upper assembly 112, a frame 114, and a lower assembly 116. The upper assembly 112 can comprise a heater (not shown) for heating the process chamber, the substrate, or the processing fluid, or a combination of two or more thereof. Alternately, a heater is not required. The frame 114 can include means for flowing a processing fluid through the processing chamber 108. In one example, a circular flow pattern can be established, and in another example, a substantially linear flow pattern can be established. Alternately, the means for flowing can be configured differently. The lower assembly 116 can comprise one or more lifters (not shown) for moving the chuck 118 and/or the substrate 105. Alternately, a lifter is not required.

In one embodiment, the process module 110 can include a holder or chuck 118 for supporting and holding the substrate 105 while processing the substrate 105. The holder or chuck 118 can also be configured to heat or cool the substrate 105 before, during, and/or after processing the substrate 105. Alternately, the process module 110 can include a platen for supporting and holding the substrate 105 while processing the substrate 105.

A transfer system (not shown) can be used to move a substrate into and out of the processing chamber 108 through a slot (not shown). In one example, the slot can be opened and closed by moving the chuck, and in another example, the slot can be controlled using a gate valve.

The substrate can include semiconductor material, metallic material, dielectric material, ceramic material, or polymer material, or a combination of two or more thereof. The semiconductor material can include Si, Ge, Si/Ge, or GaAs. The metallic material can include Cu, Al, Ni, Pb, Ti, Ta, or W, or combinations of two or more thereof. The dielectric material can include Si, O, N, or C, or combinations of two or more thereof. The ceramic material can include Al, N, Si, C, or O, or combinations of two or more thereof.

The recirculation system can be coupled to the process module 110 using one or more inlet lines 122 and one or more outlet lines 124. The recirculation system 120 can comprise one or more valves for regulating the flow of a supercritical processing solution through the recirculation system and through the process module 110. The recirculation system 120 can comprise any number of back-flow valves, filters, pumps, and/or heaters (not shown) for maintaining a supercritical processing solution and flowing the supercritical process solution through the recirculation system 120 and through the processing chamber 108 in the process module 110.

Processing system 100 can comprise a chemistry supply system 130. In the illustrated embodiment, the chemistry supply system is coupled to the recirculation system 120 using one or more lines 135, but this is not required for the invention. In alternate embodiments, the chemical supply system can be configured differently and can be coupled to different elements in the processing system. For example, the chemistry supply system 130 can be coupled to the process module 110.

The chemistry supply system 130 can comprise a cleaning chemistry assembly (not shown) for providing cleaning chemistry for generating supercritical cleaning solutions within the processing chamber. The cleaning chemistry can include peroxides and a fluoride source. For example, the peroxides can include hydrogen peroxide, benzoyl peroxide, or any other suitable peroxide, and the fluoride sources can include fluoride salts (such as ammonium fluoride salts), hydrogen fluoride, fluoride adducts (such as organic-ammonium fluoride adducts) and combinations thereof.

Further details of fluoride sources and methods of generating supercritical processing solutions with fluoride sources are described in U.S. patent application Ser. No. 10/442,557, filed May 10, 2003, and titled “TETRA-ORGANIC AMMONIUM FLUORIDE AND HF IN SUPERCRITICAL FLUID FOR PHOTORESIST AND RESIDUE REMOVAL”, and U.S. patent application Ser. No. 10/321,341, filed Dec. 16, 2002, and titled “FLUORIDE IN SUPERCRITICAL FLUID FOR PHOTORESIST POLYMER AND RESIDUE REMOVAL,” both incorporated by reference herein.

In addition, the cleaning chemistry can include chelating agents, complexing agents, oxidants, organic acids, and inorganic acids that can be introduced into supercritical carbon dioxide with one or more carrier solvents, such as N,N-dimethylacetamide (DMAc), gamma-butyrolactone (BLO), dimethyl sulfoxide (DMSO), ethylene carbonate (EC), N-methylpyrrolidone (NMP), dimethylpiperidone, propylene carbonate, and alcohols (such a methanol, ethanol and 1-propanol).

The chemistry supply system 130 can comprise a rinsing chemistry assembly (not shown) for providing rinsing chemistry for generating supercritical rinsing solutions within the processing chamber. The rinsing chemistry can include one or more organic solvents including, but not limited to, alcohols and ketones. In one embodiment, the rinsing chemistry can comprise sulfolane, also known as thiocyclopenatne-1,1-dioxide, (Cyclo)tetramethylene sulphone and 1,3,4,5-tetrahydrothiophene-1,1-dioxide, which can be purchased from a number of venders, such as Degussa Stanlow Limited, Lake Court, Hursley Winchester SO21 1LD UK.

The chemistry supply system 130 can comprise a curing chemistry assembly (not shown) for providing curing chemistry for generating supercritical curing solutions within the processing chamber.

The processing system 100 can comprise a carbon dioxide supply system 140. As shown in FIG. 1, the carbon dioxide supply system 140 can be coupled to the process module 110 using one or more lines 145, but this is not required. In alternate embodiments, carbon dioxide supply system 140 can be configured differently and coupled differently. For example, the carbon dioxide supply system 140 can be coupled to the recirculation system 120.

The carbon dioxide supply system 140 can comprise a carbon dioxide source (not shown) and a plurality of flow control elements (not shown) for generating a supercritical fluid. For example, the carbon dioxide source can include a CO₂ feed system, and the flow control elements can include supply lines, valves, filters, pumps, and heaters. The carbon dioxide supply system 140 can comprise an inlet valve (not shown) that is configured to open and close to allow or prevent the stream of supercritical carbon dioxide from flowing into the processing chamber 108. For example, controller 180 can be used to determine fluid parameters such as pressure, temperature, process time, and flow rate.

The processing system 100 can also comprise a pressure control system 150. As shown in FIG. 1, the pressure control system 150 can be coupled to the process module 110 using one or more lines 155, but this is not required. In alternate embodiments, pressure control system 150 can be configured differently and coupled differently. The pressure control system 150 can include one or more pressure valves (not shown) for exhausting the processing chamber 108 and/or for regulating the pressure within the processing chamber 108. Alternately, the pressure control system 150 can also include one or more pumps (not shown). For example, one pump may be used to increase the pressure within the processing chamber, and another pump may be used to evacuate the processing chamber 108. In another embodiment, the pressure control system 150 can comprise means for sealing the processing chamber. In addition, the pressure control system 150 can comprise means for raising and lowering the substrate and/or the chuck.

Furthermore, the processing system 100 can comprise an exhaust control system 160. As shown in FIG. 1, the exhaust control system 160 can be coupled to the process module 110 using one or more lines 165, but this is not required. In alternate embodiments, exhaust control system 160 can be configured differently and coupled differently. The exhaust control system 160 can include an exhaust gas collection vessel (not shown) and can be used to remove contaminants from the processing fluid. Alternately, the exhaust control system 160 can be used to recycle the processing fluid.

Controller 180 can use pre-process data, process data, and post-process data. For example, pre-process data can be associated with an incoming substrate. This pre-process data can include lot data, batch data, run data, composition data, and history data. The pre-process data can be used to establish an input state for a wafer. Process data can include process parameters. Post processing data can be associated with a processed substrate.

The controller 180 can use the pre-process data to predict, select, or calculate a set of process parameters to use to process the substrate. For example, this predicted set of process parameters can be a first estimate of a process recipe. A process model can provide the relationship between one or more process recipe parameters or set points and one or more process results. A process recipe can include a multi-step process involving a set of process modules. Post-process data can be obtained at some point after the substrate has been processed. For example, post-process data can be obtained after a time delay that can vary from minutes to days. The controller can compute a predicted state for the substrate based on the pre-process data, the process characteristics, and a process model. For example, a cleaning rate model can be used along with a contaminant level to compute a predicted cleaning time. Alternately, a rinse rate model can be used along with a contaminant level to compute a processing time for a rinse process.

It will be appreciated that the controller 180 can perform other functions in addition to those discussed here. The controller 180 can monitor the pressure, temperature, flow, or other variables associated with the processing system 100 and take actions based on these values. For example, the controller 180 can process measured data, display data and/or results on a GUI screen, determine a fault condition, determine a response to a fault condition, and alert an operator. The controller 180 can comprise a database component (not shown) for storing input and output data.

In a supercritical cleaning/rinsing process, the desired process result can be a process result that is measurable using an optical measuring device. For example, the desired process result can be an amount of contaminant in a via or on the surface of a substrate. After each cleaning process run, the desired process result can be measured.

FIG. 2 illustrates a simplified block diagram of a recirculation subassembly in accordance with an embodiment of the invention. In the illustrated embodiment, a recirculation subassembly 210 is shown that includes an input 212, an output 214, a pump assembly 220, and a bypass assembly 230. In alternate embodiments, different configurations can be used. For example, the recirculation subassembly 210 can be a portion of the recirculation system 120 (FIG. 1).

As shown in FIG. 2, an input 212 of the recirculation subassembly 210 can be coupled to one or more of the lines (122 FIG. 1), and an output 214 of the recirculation subassembly 210 can be coupled to one or more of the lines (124 FIG. 1). In addition, the input 212 of the recirculation subassembly 210 can be coupled to the pump assembly inlet 221; the pump assembly outlet 222 can be coupled to the input 231 of the bypass assembly 230; the output 214 of the recirculation subassembly 210 can be coupled to the bypass assembly outlet 232. In an alternate embodiment, input 212 and/or output 214 may not be required.

The pump assembly 220, which can include a pump (not shown) and a motor (not shown), can have an operating pressure up to 5,000 psi. The pump assembly can have an operating temperature up to 250 degrees Celsius. The pump assembly 220 can be used to pump a supercritical fluid that can include supercritical carbon dioxide or supercritical carbon dioxide admixed with an additive or solvent. A coolant fluid can be flowed through the pump assembly.

The pump assembly 220 can include a centrifugal impeller (not shown) that can rotate within the pump assembly 220 to pump fluid from a pump inlet 221 to a pump outlet 222. The pump assembly 220 can be coupled to a controller (180 FIG. 1) using control line 225 to control the operation of the pump assembly 220. In an alternate embodiment, the pump assembly 220 may include a controller (not shown) suitable for operating the pump assembly 220. In another embodiment, the pump assembly 220 may include one or more filters (not shown). For example, a filter may be included in an input path, an output path, or in both paths.

Bypass assembly 230 can include at least two multi-port valves (340 and 250), at least one filter 260, and at least one bypass line 270. The multi-port valve 240 can be coupled to a controller (180 FIG. 1) using control line 245 to control the operation of the multi-port valve 240. The multi-port valve 250 can be coupled to a controller (180 FIG. 1) using control line 255 to control the operation of the multi-port valve 250. For example, a multi-port valve can include a measuring device (not shown) for measuring flow and/or pressure. In an alternate embodiment, a multi-port valve may include a controller (not shown) suitable for operating the multi-port valve.

Multi-port valve 240 can include an input 241 coupled to the bypass assembly input 231, a first output 242 coupled to an input end of the bypass line 270, and a second output 243 coupled to the input 261 of the filter 260. Multi-port valve 250 can include an output 251 coupled to the bypass assembly output 232, a first input 252 coupled to an output end of the bypass line 270, and a second input 253 coupled to the output 262 of the filter 260. In alternate embodiments, a different number of multi-port valves may be used, a different number of filters may be used, a different number of bypass lines may be used, and the multi-port valves may be configured differently.

Filter 260 can be constructed to filter particles that are larger than approximately 0.050 microns. Filter 260 is intended for non-continuous operation and is not intended to operate when the supercritical fluid includes a large amount of process chemistry, process residues, and/or particles. For example, the filter 260 can be switch into the recirculation loop during one or more of the decompression cycles during time T₄ shown in FIG. 2. In this example, the small amount of process chemistry, process residues, and/or particles that remain in the fluid circulating in the recirculation loop can be removed by the filter.

In one embodiment, the flow path length for the bypass line 270 can be made to be substantially equal to the flow path length for the filter 260 and the associated piping. Alternately, the flow path length for the bypass line 270 may be made as short as possible to reduce particle contamination.

Bypass line 270 can be used for continuous operation or substantially continuous operation. For example, the bypass line 270 can be switch out of the recirculation loop during one or more of the decompression cycles during time T₄ shown in FIG. 2.

During substrate processing, having a filter in the recirculation loop can have a negative affect on the process. For example, a filter can affect the process chemistry, the process pressure, the process flow, the process temperature, and the process uniformity. In one embodiment, the bypass line 270 is coupled into the recirculation loop during a major portion of the substrate processing so that the filter's impact on the process is minimized.

In another embodiment, filter 260 can be used during a maintenance or system cleaning operation in which cleaning chemistry is used to remove process by-products and/or particles from the interior surfaces of the system. This is a preventative maintenance operation that prevents material from adhering to the interior surfaces of the system that can be dislodged later during processing and that can cause unwanted particle deposition on a substrate. In addition, the filter 260 can be replaced and/or cleaned during the bypass mode.

FIG. 3 illustrates an exemplary graph of pressure versus time for a supercritical process step in accordance with an embodiment of the invention. In the illustrated embodiment, a graph 300 of pressure versus time is shown, and the graph 300 can be used to represent a supercritical cleaning process step, a supercritical rinsing process step, or a supercritical curing process step, or a combination thereof. Alternately, different pressures, different timing, and different sequences may be used for different processes.

Now referring to both FIGS. 1, 2, and 3, prior to an initial time T₀, the substrate to be processed can be placed within the processing chamber 108 and the processing chamber 108 can be sealed. For example, during cleaning and/or rinsing processes, a substrate can have post-etch and/or post-ash residue thereon. The substrate, the processing chamber, and the other elements in the recirculation loop 115 (FIG.1) can be heated to an operational temperature. For example, the operational temperature can range from 40 to 300 degrees Celsius.

From the initial time T₀ through a first duration of time T₁, the processing chamber 108 and the other elements in the recirculation loop 115 (FIG.1) can be pressurized. For example, a supercritical fluid, such as substantially pure CO₂, can be used to pressurize the processing chamber 108 and the other elements in the recirculation loop 115 (FIG.1). During time T₁, a pump, such as pump 220 (FIG. 2), can be started and can be used to circulate the supercritical fluid through the processing chamber 108 and the other elements in the recirculation loop 115 (FIG.1).

During a first portion of the time T₁, a filter, such as filter 260 (FIG. 2), can be switched into the flow path and can be used to filter the supercritical fluid circulating through the processing chamber 108 and the other elements in the recirculation loop 115 (FIG.1). For example, the recirculation subassembly can be operated in a filter mode. In addition, during a second portion of the time T₁, the filter can be switched out of the flow path and a bypass line, such as bypass line 270 (FIG. 2), can be used as an element in the recirculation loop. For example, the recirculation subassembly can be operated in a bypass mode.

In one embodiment, when the pressure in the processing chamber 108 exceeds a critical pressure Pc (1,070 psi), process chemistry can be injected into the processing chamber 108, using the process chemistry supply system 130. In addition, the filter can be switched out of the recirculation loop and the bypass line can be switched into the recirculation loop before the process chemistry is injected. In alternate embodiments, process chemistry may be injected into the processing chamber 108 before the pressure exceeds the critical pressure Pc (1,070 psi) using the process chemistry supply system 130. For example, the injection(s) of the process chemistries can begin upon reaching about 1100-1200 psi. In other embodiments, process chemistry is not injected during the T₂ period.

In one embodiment, process chemistry is injected in a linear fashion, and the injection time can be based on a recirculation time. For example, the recirculation time can be determined based on the length of the recirculation path and the flow rate. In other embodiments, process chemistry may be injected in a non-linear fashion. For example, process chemistry can be injected in one or more steps.

The process chemistry can include a cleaning agent, a rinsing agent, or a curing agent, or a combination thereof that is injected into the supercritical fluid. One or more injections of process chemistries can be performed over the duration of time T₁ to generate a supercritical processing solution with the desired concentrations of chemicals. The process chemistry, in accordance with the embodiments of the invention, can also include one more or more carrier solvents.

Still referring to both FIGS. 1, 2, and 3, during a second time T₂, the supercritical processing solution can be re-circulated over the substrate and through the processing chamber 108 using the recirculation system 120, such as described above. In one embodiment, process chemistry is not injected during the second time T₂. Alternatively, process chemistry may be injected into the processing chamber 108 during the second time T₂ or after the second time T₂.

The processing chamber 108 can operate at a pressure above 1,500 psi during the second time T₂. For example, the pressure can range from approximately 2,500 psi to approximately 3,100 psi, but can be any value so long as the operating pressure is sufficient to maintain supercritical conditions. The supercritical processing solution is circulated over the substrate and through the processing chamber 108 using a pump in the recirculation system 120, such as described above. The supercritical conditions within the processing chamber 108 and the other elements in the recirculation loop 115 (FIG.1) are maintained during the second time T₂, and the supercritical processing solution continues to be circulated over the substrate and through the processing chamber 108 and the other elements in the recirculation loop 115 (FIG.1). A pump, such as pump 220 (FIG. 2), can be used to regulate the flow of the supercritical processing solution through the processing chamber 108 and the other elements in the recirculation loop 115 (FIG.1).

In one embodiment, during the second time T₂, the filter can be switched out of the flow path and a bypass line, such as bypass line 270 (FIG. 2), can be used as an element in the recirculation loop. For example, the recirculation subassembly 210 can be operated in a bypass mode. Alternately, the recirculation subassembly 210 may be operated in a filter mode during a portion of the second time T₂.

Still referring to both FIGS. 1, 2, and 3, during a third time T₃ a push-through process can be performed. During the third time T₃, a new quantity of supercritical carbon dioxide can be fed into the processing chamber 108 and the other elements in the recirculation loop 115 from the carbon dioxide supply system 140, and the supercritical cleaning solution along with process residue suspended or dissolved therein can be displaced from the processing chamber 108 and the other elements in the recirculation loop 115 through the exhaust control system 160. In an alternate embodiment, supercritical carbon dioxide can be fed into the recirculation system 120 from the carbon dioxide supply system 140, and the supercritical cleaning solution along with process residue suspended or dissolved therein can also be displaced from the processing chamber 108 and the other elements in the recirculation loop 115 through the exhaust control system 160.

In one embodiment, during the third time T₃, the filter can be switched out of the flow path and a bypass line, such as bypass line 270 (FIG. 2), can be used as an element in the recirculation loop. For example, the recirculation subassembly 210 can be operated in a bypass mode. Alternately, the recirculation subassembly 210 may be operated in a filter mode during a portion of the third time T₃.

In the illustrated embodiment shown in FIG. 2, a single second time T₂ is followed by a single third time T₃, but this is not required. In alternate embodiments, other time sequences may be used to process a substrate.

After the push-through process is complete, a decompression process can be performed. In an alternate embodiment, a decompression process is not required. During a fourth time T₄, the processing chamber 108 can be cycled through a plurality of decompression and compression cycles. The pressure can be cycled between a first pressure P₃ and a second pressure P₄ one or more times. In alternate embodiments, the first pressure P₃ and a second pressure P₄ can vary. In one embodiment, the pressure can be lowered by venting through the exhaust control system 160. For example, this can be accomplished by lowering the pressure to below approximately 1,500 psi and raising the pressure to above approximately 2,500 psi. The pressure can be increased by adding high-pressure carbon dioxide.

In one embodiment, during a first portion of the fourth time T₄, the filter can be switched out of the flow path and a bypass line 270 can be used as an element in the recirculation loop. For example, the recirculation subassembly 210 can be operated in a bypass mode. During a second portion of the time T₄, a filter 260 can be switched into the flow path and can be used to filter the supercritical fluid circulating through the processing chamber 108 and the other elements in the recirculation loop 115 (FIG.1). For example, the recirculation subassembly can be operated in a filter mode.

Alternately, the recirculation subassembly can be operated in a bypass mode during the fourth time T₄.

During a fifth time T₅, the processing chamber 108 can be returned to lower pressure. For example, after the decompression and compression cycles are complete, then the processing chamber can be vented or exhausted to atmospheric pressure. For substrate processing, the chamber pressure can be made substantially equal to the pressure inside of a transfer chamber (not shown) coupled to the processing chamber. In one embodiment, the substrate can be moved from the processing chamber into the transfer chamber, and moved to a second process apparatus or module to continue processing.

In one embodiment, during the fifth time T₅, the filter can be switched out of the flow path and a bypass line 270 can be used as an element in the recirculation loop. For example, the recirculation subassembly 210 can be operated in a bypass mode.

In the illustrated embodiment shown in FIG. 3, the pressure returns to an initial pressure P₀, but this is not required for the invention. In alternate embodiments, the pressure does not have to return to P₀, and the process sequence can continue with additional time steps such as those shown in time steps T₁, T₂, T₃, T₄, or T₅

The graph 300 is provided for exemplary purposes only. It will be understood by those skilled in the art that a supercritical processing step can have any number of different time/pressures or temperature profiles without departing from the scope of the invention. Further, any number of cleaning and rinse processing sequences with each step having any number of compression and decompression cycles are contemplated. In addition, as stated previously, concentrations of various chemicals and species within a supercritical processing solution can be readily tailored for the application at hand and altered at any time within a supercritical processing step.

While the invention has been described in terms of specific embodiments incorporating details to facilitate the understanding of the principles of construction and operation of the invention, such reference herein to specific embodiments and details thereof is not intended to limit the scope of the claims appended hereto. It will be apparent to those skilled in the art that modifications may be made in the embodiments chosen for illustration without departing from the spirit and scope of the invention. 

1. An apparatus, comprising: a processing chamber having a processing chamber inlet and a processing chamber outlet; a recirculation subassembly having an inlet coupled to the processing chamber outlet and an outlet coupled to the processing chamber inlet, wherein the recirculation subassembly comprises a pump assembly and a bypass assembly coupled to the pump assembly, the bypass assembly comprising a first branch and a second branch; and a controller coupled to the bypass assembly for switching the bypass assembly between a first mode and a second mode, wherein when the bypass circuit is in a first mode, a first path is establish through the recirculation subassembly that includes the pump assembly and the first branch, and when the bypass circuit is in a second mode, a second path is establish through the recirculation subassembly that includes the pump assembly and the second branch.
 2. The apparatus of claim 1, wherein the second branch contains a filter and the first branch contains a bypass line.
 3. The apparatus of claim 1, further comprising: a fluid supply system coupled to the processing chamber, wherein a fluid contained in the fluid supply system is provided to the processing chamber and flows through the pump assembly, through the bypass assembly, and through the processing chamber.
 4. The apparatus of claim 3, wherein the pump assembly, the bypass assembly, and the processing chamber form a circulation loop.
 5. The apparatus of claim 2, wherein the bypass assembly comprises: a first valve having an input, a first output, and a second output, the first output coupled to the filter the second output coupled to the bypass line; and a second valve having a first input coupled to the filter, a second input coupled to the bypass line, and an output coupled to the processing chamber.
 6. The apparatus of claim 1, wherein the processing chamber is a supercritical processing chamber.
 7. The apparatus of claim 3, wherein the fluid comprises substantially pure CO₂.
 8. An apparatus, comprising: means for circulating a supercritical fluid over a substrate in a processing chamber, thereby creating a contaminated process fluid; means for filtering the contaminated process fluid coupled to the means for circulating and the processing chamber; means for bypassing coupled to the means for circulating and the processing chamber, wherein the means for bypassing comprises means for bypassing the means for filtering; and means for controlling the means for bypassing, wherein when the means for bypassing is in a first mode, the means for circulating, the means for bypassing and the processing chamber define a first path containing a bypass line, and when the means for bypassing is in a second mode, the means for circulating, the means for filtering, and the processing chamber define a second path containing a filter.
 9. A method of circulating a first material and a second material in a processing system, comprising: circulating the first material through a processing chamber over a first processing path through a recirculation subassembly during a first processing cycle; and circulating a second material through the processing chamber over a second processing path through a recirculation subassembly during a second processing cycle, the second processing path different from the first processing path.
 10. The method of claim 9, wherein the second processing path comprises a filter and the first processing path comprises a bypass line.
 11. The method of claim 9, wherein one of the first processing cycle and the second processing cycle comprises supercritical processing.
 12. The method of claim 9, wherein the second material is carbon dioxide.
 13. The method of claim 12, wherein the carbon dioxide is in a supercritical state.
 14. The method of claim 12, wherein the second material further comprises a surfactant.
 15. The method of claim 12, wherein the second material further comprises an amide or an amine. 